NiMH off the charger can be ~+1.45VDC. that's how "Tony M" came up with his 4.2V number. 1.2VDC is just the nominal voltage similar to how Li-ion cells are given as +3.7VDC when off the charger they are typically >+4.1VDC (up to +4.2VDC).
so, please consider the +4.2VDC number Tony_M came up with instead of the +3.6VDC nominal series voltage for three NiMH cells.